1. Field Of The Invention
The present invention relates to cellular foam compositions characterized by low friability, improved strength properties and good flame retardancy. More particularly, the invention relates to carbodiimide-isocyanurate foams containing urethane linkages prepared by condensing an organic polyisocyante and a primary hydroxy-terminated polyoxyalkylene or polyester polyol in the presence of certain catalyst systems.
2. The Prior Art
In our copending U.S. patent applications Ser. Nos. 427,035 and 427,122, both filed Dec. 21, 1973, now U.S. Pat. Nos. 3,894,972 and 3,887,501, respectively, we disclose the preparation of foam compositions characterized by carbodiimide and isocyanurate linkages by condensing an organic polyisocyanate in the presence of a catalyst system comprising (a) furfuryl alcohol or methanol and (b) a tertiary amine trimerization catalyst. Also disclosed therein is that the foam compositions may be modified to contain urethane linkages by carrying out the condensation in the presence of a polyol and a urethane catalyst. The present invention is an improvement in the process and compositions described in our aforementioned applications.